Flexible pressure-type joint for rigid tubing

ABSTRACT

A pressure-type joint for connecting one tubular element formed of non-flexible plastics material and provided with an externally threaded male portion, into a second tubular element formed of glass and having an internally threaded female portion. The externally threaded element is provided with a central, longitudinal bore for receiving a thermometer or the like, and the threads of this element are of sufficiently reduced dimensions with respect to the internal threads of the other element to provide an annular clearance between the threads to permit relative angular movement of the joined elements so as to minimize chances of breaking the thermometer or the like. Compressible O-rings are interposed between the threaded end of each element and a radial shoulder formed on the opposite element to insure a tight seal of the joint, despite relative annular movement of the joined elements, one of the O-rings surrounding the thermometer in the externally threaded element and serving the dual function of sealing the joint and also the inserted thermometer or the like.

United States Patent DeWoody [54] FLEXIBLE PRESSURE-TYPE JOINT FOR RIGIDTUBING [72] Inventor: Charles M. DeWoody, Vineland,

[73] Assignee: Ace Glass Incorporated, Vineland,

[22] Filed: Jan. 7, 1970 [21] Appl. No.: 1,226

Related US. Application Data [63] Continuation-in-part of Ser. No.673,376, Oct.

6, 1967, Pat. No. 3,499,670.

[52] US. Cl ..285/l33 R, 285/223, 285/346, 285/351, 285/353, 285/355,285/423 [51] Int. Cl ..F16l 47/00 [58] Field of Search..285/35l, 353,346, 133 R, 138, 285/355, 340, 223, 423, DIG. 12

[451 Oct. 3, 1972 FOREIGN PATENTS 0R APPLICATIONS 1,060,239 3/ 1967Great Britain ..285/ 133 R Primary Examiner-Dave W. Arola AttorneyG.Mallet Prevost ABSTRACT A pressure-type joint for connecting one tubularelement formed of non-flexible plastics material and provided with anexternally threaded male portion, into a second tubular element formedof glass and having an internally threaded female portion. Theexternally threaded element is provided with a central, longitudinalbore for receiving a thermometer or the like, and the threads of thiselement are of sufficiently reduced dimensions with respect to theinternal threads of the other element to provide an annular clearancebetween the threads to permit relative angular movement of the joinedelements so as to minimize chances of breaking the thermometer or thelike. Compressible O-rings are interposed between the threaded end ofeach element and a radial shoulder formed on the opposite element toinsure a tight seal of the joint, despite relative annular movement ofthe joined elements, one of the O-rings surrounding the thermometer inthe externally threaded element and serving the dual function of sealingthe joint and also the inserted thermometer or the like.

6 Claims, 10 Drawing Figures PATENTEilnms m SHEET 1 BF 2 Ila F/GE

' INVENTOR @HARL E5 M- De WOOD) A TTORNEY FLEXIBLE PRESSURE-TYPE JOINTFOR- RIGID TUBING This application is a continuation-in-part of mycopending application Ser. No. 673,376, filed Oct. 6, 1967 and now US.Pat. No. 3,499,670.

BACKGROUND OF INVENTION In the past, there have been problems insecuring a true pressure-tight seal when coupling two sections of glasstubing, such for example, as used in laboratories and chemical systems.Ground conical couplings require springs which must be of a low tensionand, therefore, tend to blow out readily.

A ground ball and socket joint is fastened together with a clamp, and ifsufficient pressure is exerted on the glass to create a seal which iseffective at more than 75 lbs. psig, the rate of breakage is verysignificant.

Flange-type joints are very limited in flexibility, and also are proneto breakage from over-tightening the clamp to make seals effective atover 50 lbs. psig.

Flexible joints which rely on the flexibility of the threaded couplingelements per se for angular relative movement will deform sufficientlyto form a leak path and do not provide sufficient thread shear forceresistance.

SUMMARY In glass chemical equipment, a certain degree of angularflexibility is necessary to compensate for thermal expansion andmisalignment of equipment for feeding from reservoirs into reactors andthe like. The joint of the present invention provides increased angularflexibility, reduces breakage, and insures a tight seal at pressure over200 lbs. psig, which is above the normal operating pressures for glassstandard wall pipe equipment.

In my said copending application, two internally threaded sections ofglass tubing are coupled by a substantially cylindrical element formedof a plastic material or filled plastics material softer than the glasstubing, and having a central, annular, radial flange which terminatesaxially at opposite ends in externally threaded nipples. The externalthreads of the nipples are of sufficiently reduced dimensions withrespect to the internal threads of the glass tubing to provide anannular clearance which permits substantial angular relative movement ofthe glass tubing. Annular compressible seals are interposed between theends of the glass tubing and the adjacent faces of the respectivecentral flange. 1

This same principle is employed in the present invention, in connectionwith various other items of laboratory equipment, such as threaded glassthermometer adapters, where a thermometer extends. through a threadedplastic bushing which tightens into a complementary glass female member.The difference in the thread dimensions of the bushing and glass memberprovide the desired flexibility, and suitable O-rings are employed tomaintain a tight seal, despite relative angular movement of the bushingand glass member. This angular flexibility is effective in minimizingthermometer breakage.

THE DRAWINGS Referring to the drawings in which numerals of likecharacter designate similar parts throughout the several views:

FIG. 1 is an exploded, fragmentary, perspective illustrating the partsof the joint; I

FIG. 2 is a view in side elevation showing the assembled joint with thetwo coupled sections of glass tubing axially aligned;

FIG. 3 is a similar view illustrating the relative angular movement ofthe two sections of tubing;

FIG. 4 is an enlarged, longitudinal, sectional view, illustrating thedifferences in the respective thread dimensions of a tube section andcoupling nipple;

FIG. 5 is a similar view showing a section of tubing I undergoingrelative angular movement;

FIG. 6 shows a modification for use in slidably coupling a tube ofreduced diameter to a larger tube;

FIG. 7 is a sectional view of a similar modification for use as athermometer adapter;

FIG. 8 is another generally similar modification showing a differentarrangement of O-rings;

FIG. 9 shows the device of the present invention for use in sealing athermometer into a flask; and

FIG. 10 is a still further modification wherein the coupling embodiesthe reverse construction of that illustrated in FIGS. 1-3, wherein theplastic component has an internal flange and is internally threaded, andthe glass pipe has an external thread.

DETAILED DESCRIPTION In the drawings, 10 and 10a represent two sectionsof glass tubing to be coupled. In the form of the invention illustrated,these sections of tubing respectively terminate at one end in bellportions 11, 11a, which are internally threaded as at 12, FIGS. 4 and 5.While the invention is primarily concerned with the coupling of sectionsof glass tubing, it may be noted that rigid tubing formed of suitableplastics and other materials is also contemplated, and, therefore, inthe claims, the terms glass and rigid are intended to also embrace theseother materials.

The coupling element of the invention is generally indicated at 14, andcomprises an annular, radial flange 15 which terminates axially atopposite ends in integral, externally threaded nipples 16 and 16a. Thecoupling is preferably formed of such plastics as nylon,polytetrafluoroethylene (Teflon), polytrifluorochloroethylene (Kel-F),and the like, although hard rubber or other suitable material may beemployed. Hence, in the claims, the term plastics material is intendedto include both plastics of the type above referred to, as well as hardrubber and other suitable material including filled plastics so long asits surface does not abrade the mating threads.

The nipples 16 and 16a are externally threaded as at 17, and, as bestseen in FIG. 4, the nipple threads are of sufficiently reduceddimensions with respect to the internal threads 12 of the bell 1 1, topermit relative angular movement of the coupled tubing sections, as seenin FIG. 5. The difference between the thread dimensions of the nippleand bell can vary so long as there is an area of threaded engagement ofa minimum depth of one-half a thread, which is sufficient to providemechanical thread shear force resistance to effect tight engagement ofthe threads when the joint is completely assembled. Also, the respectivethread contours may differ, that is, one can be curved in cross-section,and the other V-shaped, provided there is a sufficient area of threadedengagement.

Opposite faces of the annular flange are recessed as at 19 to receivesuitable seals, such as the O-rings 18 shown in the drawing. The annularlips of the recesses 19 are longitudinally offset from the correspondingends of the bells 11 so as to accommodate the required relative movementin the angular adjustment of the tubing sections. The cross-sectionalcontour of the grooves 19 is semi-eliptical so that the inner edges ofthe lips 20 overlie the outer peripheries of the O-rings 18 to retainthem in place, while, at the same time, accommodating the deformation ofthe rings under compression when the tubing sections are undergoingrelative angular adjustment, as best seen in FIG. 5.

Preferably, the bores 13 of the tubing sections 10, 10a are of the samediameter as the bore 22 of the nipples 16, 16a, so as to avoid anyrestriction of flow through the joint.

In addition to the O-rings 18, supplemental sealing rings 21 ofcompressible material may be employed between the bases of the bells 11,11a and the adjacent ends of the nipples 16, 16a.

It is also conceivable that in a modified adaptation of the invention,the reduced male threads 17 of the nipples 16, 16a may be coated with acompressible substance, substantially filling the intervening spacesbetween the complementary threads, so that the joint relies on thecompressibility of this material for angular flexing of the coupledtubing sections.

As previously noted, the difference in dimensions of the coactingthreads 12 and 17 is controlled so as to maintain a mechanical threadshear force resistance as at 23 in FIG. 4, and the material of which thecoupling element 14 is formed must be sufficiently stiff and nonflexibleto provide such mechanical thread shear force resistance as to effect atight engagement of the threads. Thus, when the bell 1 l is screwed ontothe nipple 16, a tight threaded engagement is effected to insure a tightcompression and sealing engagement with the O-ring 18. However, uponangular movement of the tubing section 10 with respect to the couplingelement, the spaces 24 between the non-contacting areas of the threads,accommodate the angular adjustment of the tubing sections on thenipples, while a tight seal is maintained between the bell and theflange by virtue of the compressible O-ring 18.

The invention provides an angularly adjustable joint which will insure atight seal at high pressures of from 15 psi to the order of 200 psi.

Referring now to FIGS. 6-10, which illustrate the modified embodimentsof the invention covered by the present continuation-in-partapplication, it will be noted that the same basic principle ofdifferences in thread diameters and coacting sealing rings is employedto obtain the desired flexibility between the coupled elements. In FIG.6, the joint is designed to couple a smaller tube to a tube 31 of largerdiameter. The tube 31 is provided at its end with an enlarged bell 32having internal threads 33. A plastic adapter 34,

having a radially enlarged head 35, is externally threaded as at 36. Asin the previously described form of the invention, the external threads36 of the adapter are of sufiiciently reduced dimensions with respect tothe internal threads 33 of the tubing bell 32 to provide an annularclearance which permits substantial angular relative movement of theglass tubing 31 with respect to the adapter 34.

In this form of the invention, sealing rings 37 are interposed betweenthe flat surface or shoulder formed by the head 35 and the end of thebell 32, and the longitudinal spacing between the end of the bell andthe shoulder of the head 35 is maintained by the sealing ring 37, so asto accommodate angular relative movement of the adapter and tubing bellwhen the sealing ring is compressed.

Still referring to FIG. 6, it will be noted that at the base of the bell32, the tube 31 is provided with an inwardly directed, annular shoulder38 which is curved in cross section as shown. This shoulder supports asecond sealing ring 39 which is engaged by a projection 40 on thethreaded extremity of the adapter 34, there being an annular space 41between the projection 40 and the inner periphery of the bell 32 toaccommodate angular movement of the adapter. In this form of curvedshoulder 38, it will be observed that the sealing ring 39 serves thedual purpose of sealing the end of the adapter with respect to the bell,as is the case with the seal 21 of FIGS. 4 and 5, and also seals thebell around the outer periphery of the smaller tube 30. Thus, when theadapter is tightened into the bell, the sealing rings 37 and 39 maintaina tight seal despite angular manipulation of the adapter and bell 32,and the seal 39 main tains this tight seal against the periphery of thesmaller tube 30 when the latter is slid or moved in the adapter andlarger tube.

FIG. 7 illustrates a generally similar modification for handling lowerpressures, and wherein the smaller tube 30 is replaced by a glass arm30a in a feed-through arrangement to manipulate materials in a dry boxor other type chamber (not shown) with a controlled internal atmosphere.In this form of the invention, the O- ring 39 may be eliminated and acompressible seal 39a may be interposed between the bore of the head 35and the periphery of the arm 30a. The arm 30a is in slidable engagementwith the adapter 34 and can be rotated.

FIG. 8 shows the same embodiment as in FIG. 7, but arranged for highvacuum work such as pressures of IO Torr., where seals 39 and 390 may beused in addition to seal 37 to lower the intrinsic leak rate to theorder of 10' liter atmosphere/day.

FIG. 9 shows one use of the invention of the presentcontinuation-inpart, such for example, as a flask 42 having athermometer adapter 34 arranged in its neck 31a, the latter being theequivalent of the glass tube 31 in FIGS. 6, 7 and 8.

FIG. 10 shows a modification of a coupling for performing substantiallythe same function as the coupling of FIGS. 1-5, but with a reversal ofthe flange and thread arrangement. In this modified form, the plasticcoupling element 43, instead of having externally threaded nipples as inthe previous forms, is provided with internal threads 44, and aninwardly directed annular flange 45 forms the seal-engaging shoulder.This shoulder is provided on its fore and aft faces with annular grooves46 into which the O-rings 39 are compressed between the ends of theexternally threaded portions 48 of the glass tubing sections 47 whichare being coupled.

In all of these forms of the invention, the extensions 40 on the ends ofthe externally threaded male members may be eliminated and the ends ofthese members shaved off to obtain a precise compression of the coactingO-rings. I

It will be apparent that the joint of the invention clearlydistinguishes and represents an improvement over purely flexiblecoupling elements which rely entirely on their flexibility for angularadjustment. As before pointed out, a wholly flexible coupling elementdeforms sufficiently to form a leak path, and, furthermore, would notprovide the necessary thread shear force resistance.

From the foregoing, it is believed that the invention may be readilyunderstood by those skilled in the art without further description.

lclaim:

1. A pressure-type joint for the internally threaded end of a firsttubular element and the externally threaded end of a second tubularelement, one of said threaded elements being composed of a substantiallynon-flexible plastics material softer than that of the other threadedelement, one of said threaded elements being provided with a radialshoulder at the inner extremity of its threaded area, said externalthreads and said second threaded element being of sufficiently reduceddimensions with respect to said first threaded element and the internalthreads thereof to provide an annular clearance to permit substantialtransverse angular movement of said elements relative to each other, anannular compressible seal engaging said shoulder, which, when the jointis assembled and tightened, is of sufficient thickness to provide alongitudinal spacing between said shoulder and the end of said otherelement, said seal being sufficiently compressible when assembled toaccommodate the relative angular movement of said elements while stillmaintaining a seal, an elongated third element slidably insertablelongitudinally through said engaging threaded elements, and an annularcompressible sealing ring means engaging the periphery of saidinsertable third element between the latter and a surrounding threadedelement, said third element having sufficient clearance relative to saidthreaded elements to accommodate said angular movement.

2. A pressure-type joint for the internally threaded end of a firsttubular element and the externally threaded end of a second tubularelement, one of said threaded elements being composed of a substantiallynon-flexible plastics material softer than that of the other threadedelement, said threaded elements being provided with radial shoulders atthe inner extremities of their threaded areas, said external threads andsaid second threaded element being of sufficiently reduced dimensionswith respect to said first threaded element and the internal threadsthereof to provide an annular clearance to permit substantial transverseangular movement of said elements relative to each other, annularcompressible seals interposed between and engaging the shoulders of saidelements and the adjacent ends of the opposite elements, respectively,which, when the oint is assembled and tightened, are of sufficientthickness to provide a longitudinal spacing between each shoulder andthe adjacent end of the 0pposite element, said seals being sufficientlycompressible when assembled to accommodate the relative angular movementof said elements while still maintaining a seal, an elongated thirdelement slidably insertable longitudinally through said engagingthreaded elements, and an annular compressible sealing ring meansengaging the periphery of said insertable third element between thelatter and a surrounding threaded element.

3. A joint as claimed in claim 2, wherein the internally threadedelement is provided with an internally directed, radial shoulder and oneof said seals is interposed between said last-named shoulder and the endof the externally threaded element.

4. A joint as claimed in claim 3, wherein said lastnamed sealadditionally engages the periphery of said third element and serves thedual purpose of sealing the joint and sealing the third element withinthe externally threaded element.

5. A joint as claimed in claim 4, wherein the seal engaging surface ofsaid internally directed radial shoulder is arcuate in cross-section,with its open area directed axially of said joint.

6. A pressure-type joint for the internally threaded end of a firsttubular element and the externally threaded end of a second tubularelement, one of said elements being composed of substantiallynon-flexible plastics material softer than that of the other threadedelement, the internally threaded element being provided with an inwardlydirected radial shoulder adjacent the inner extremity of its threadedarea, said external threads and said second threaded element being ofsufficiently reduced dimensions with respect to said first threadedelement and the internal threads thereof to provide an annular clearanceto permit substantial angular transverse movement of said elementsrelative to each other, an annular, compressible seal engaging theshoulder of said internally threaded element, which, when the joint isassembled and tightened, is of sufficient thickness to provide alongitudinal spacing between said shoulder and the end of saidexternally threaded element, said seal being sufficiently compressiblewhen assembled to accommodate the relative angular movement of saidelements while still maintaining a seal, said internally threadedelement having an end which surrounds said externally threaded element,said externally threaded element having an outer cylindrical surfaceadjacent to said end of said internally threaded element, substantiallyuniformly smaller in diameter than said end of said internally threadedelement, and free of a seal thereto.

1. A pressure-type joint for the internally threaded end of a firsttubular element and the externally threaded end of a second tubularelement, one of said threaded elements being composed of a substantiallynon-flexible plastics material soFter than that of the other threadedelement, one of said threaded elements being provided with a radialshoulder at the inner extremity of its threaded area, said externalthreads and said second threaded element being of sufficiently reduceddimensions with respect to said first threaded element and the internalthreads thereof to provide an annular clearance to permit substantialtransverse angular movement of said elements relative to each other, anannular compressible seal engaging said shoulder, which, when the jointis assembled and tightened, is of sufficient thickness to provide alongitudinal spacing between said shoulder and the end of said otherelement, said seal being sufficiently compressible when assembled toaccommodate the relative angular movement of said elements while stillmaintaining a seal, an elongated third element slidably insertablelongitudinally through said engaging threaded elements, and an annularcompressible sealing ring means engaging the periphery of saidinsertable third element between the latter and a surrounding threadedelement, said third element having sufficient clearance relative to saidthreaded elements to accommodate said angular movement.
 2. Apressure-type joint for the internally threaded end of a first tubularelement and the externally threaded end of a second tubular element, oneof said threaded elements being composed of a substantially non-flexibleplastics material softer than that of the other threaded element, saidthreaded elements being provided with radial shoulders at the innerextremities of their threaded areas, said external threads and saidsecond threaded element being of sufficiently reduced dimensions withrespect to said first threaded element and the internal threads thereofto provide an annular clearance to permit substantial transverse angularmovement of said elements relative to each other, annular compressibleseals interposed between and engaging the shoulders of said elements andthe adjacent ends of the opposite elements, respectively, which, whenthe joint is assembled and tightened, are of sufficient thickness toprovide a longitudinal spacing between each shoulder and the adjacentend of the opposite element, said seals being sufficiently compressiblewhen assembled to accommodate the relative angular movement of saidelements while still maintaining a seal, an elongated third elementslidably insertable longitudinally through said engaging threadedelements, and an annular compressible sealing ring means engaging theperiphery of said insertable third element between the latter and asurrounding threaded element.
 3. A joint as claimed in claim 2, whereinthe internally threaded element is provided with an internally directed,radial shoulder and one of said seals is interposed between saidlast-named shoulder and the end of the externally threaded element.
 4. Ajoint as claimed in claim 3, wherein said last-named seal additionallyengages the periphery of said third element and serves the dual purposeof sealing the joint and sealing the third element within the externallythreaded element.
 5. A joint as claimed in claim 4, wherein the sealengaging surface of said internally directed radial shoulder is arcuatein cross-section, with its open area directed axially of said joint. 6.A pressure-type joint for the internally threaded end of a first tubularelement and the externally threaded end of a second tubular element, oneof said elements being composed of substantially non-flexible plasticsmaterial softer than that of the other threaded element, the internallythreaded element being provided with an inwardly directed radialshoulder adjacent the inner extremity of its threaded area, saidexternal threads and said second threaded element being of sufficientlyreduced dimensions with respect to said first threaded element and theinternal threads thereof to provide an annular clearance to permitsubstantial angular transverse movement of said elements relative toeach other, an annular, compressible seal engaging the shoulder of saidinternally threaded element, which, when the joint is assembled andtightened, is of sufficient thickness to provide a longitudinal spacingbetween said shoulder and the end of said externally threaded element,said seal being sufficiently compressible when assembled to accommodatethe relative angular movement of said elements while still maintaining aseal, said internally threaded element having an end which surroundssaid externally threaded element, said externally threaded elementhaving an outer cylindrical surface adjacent to said end of saidinternally threaded element, substantially uniformly smaller in diameterthan said end of said internally threaded element, and free of a sealthereto.